1. Technical Field
The invention relates generally to a rotatable connection structure, and more specifically to a rotatable and pivotable connector having an interior passageway permitting communication of fluids, solids, and gases therealong and an exterior fitting resisting disconnection of adjacent connectors.
2. Background Art
Many ball-and-socket connectors are presently in use. Generally, many of these connectors suffer from the same problem: under sufficient force, the ball of a first connector disconnects from the socket of an adjacent connector. Structurally, the socket external end may impact a surface (such as the outer socket wall of the first connector). As pivoting force is exerted on the interconnected connectors, the socket external end and impacted surface may act as a fulcrum to dislodge, or “pop,” the interconnected ball out of the socket.
Several approaches have been taken to rectify this problem. One approach is disclosed in U.S. Pat. Nos. 6,042,155 and 5,449,206, both to Lockwood. An example of two interlinked Lockwood ball-and-socket connectors 1, as disclosed in the Lockwood patents, is shown in cross-section in FIG. 1. These connectors 1, however, are relatively structurally complex, requiring an inner annular ring 2 projecting into a passageway 3 defined through the middle of the connector 1. Not only does such complexity increase manufacturing costs, but the inner annular ring 2 may serve as a limitation on the diameter of items passing through the passageway 3 (for example, a hose or tube), or may trap such items between the annular ring 3 and an inner wall 4 of the connector 1.
Multiple ball-and-socket connectors may be connected to form a single, flexible arm. The individual connectors in the arm may rotate, pivot, flex, and twist with respect to one another, and the arm may be bent into a variety of shapes and positions. Accordingly, it may be desirable to fit adjacent connectors to one another in such a manner as to permit the arm to maintain a bent position. The ability to remain stationary and support a load (without the application of tools, external supports, locking devices, and so forth) may be useful in many applications.
With respect to the many ball-and-socket connectors manufactured from polymer resins, the ability of a flexible arm to retain an attached load while in a bent or flexed position is dependent on a frictional fit between adjacent connectors. With time, the connectors may loosen, and the friction generated between adjacent connectors may diminish. In turn, this may cause the arm to bend undesirably under stresses it once may have been able to withstand. This bending is generally due to a phenomenon known as “creep.” Creep occurs when moving parts are subjected to a constant or intermittent load and, as a result of that load, gradually relax and loosen as mentioned above.
Over time, creep may cause interconnected ball-and-socket connectors to deform. A socket may distort, taking on an elliptical shape in order to relax the relatively constant strain under which it is placed. Similarly, a ball nestled within the socket may continue to apply a load force to the socket, which eventually results in the ball disengaging from the socket. This may be especially common where the arm maintains a non-linear shape for an extended time. Among other disadvantages, creep and resulting distortion may minimize the load capability, stationary holding force, and bending radius of a flexible arm.
Accordingly, there is a need in the art for an improved pivotable connector.